Ventilation system - Noise level dependent on which factors?

... there are fans inside. Even the geometry of the blades alone determines how loud it will be afterwards.

or put differently:

better slow-spinning large fans than fast-spinning (too) small propellers

First of all, many, many thanks for all your answers!! They are really very professionally written, but I still hope to have understood everything a little bit.

First of all, the question is, who actually plans such a ventilation system? Does the manufacturer specify everything and the homeowner has to install the ducts and all the rest according to the specifications? As a customer and unfortunately a layperson, can I influence the whole thing in any way at all?

A few of you wrote that it should be a high-quality ventilation device and preferably a central one. I’ll write you the text from the offer, then maybe you can tell me whether these are high-quality brands or not. I believe it is central, at least two ducts were planned in the basement for supply and exhaust air.

[*]Controlled residential ventilation with heat recovery via cross-counterflow heat exchanger Viessmann Vitovent 300W or Vaillant recoVair VAR260/4

Thanks again for your answers!

Since there isn’t much feedback here, I hope that’s because the problems rarely occur, which is somewhat reassuring :).

hm… yes, you can hear it. Not always. The system runs at different levels: 1 small/low, 4 high/large throughput. Then there are the valves that can be adjusted (at least that’s how it is with us). The airflow can sometimes sound compressed. You adjust that depending on how the house is used. For example, it should be more active when a lot of air is “used” at night and while cooking. Another thing is the device itself.

Okay, so you have to do it manually, that wasn't clear to me either... In the mentioned (noisy) house, despite active ventilation, all windows were wide open, I wondered if the system was working at full capacity because of that, but that is probably ruled out.

You also write: "the device itself". Can you (or others) assess my devices to choose from?
Viessmann Vitovent 300W or Vaillant recoVair VAR260/4

Maybe someone else can also say something about my question?
First of all the question, who actually plans such a ventilation system? Does the manufacturer specify everything and the homeowner just has to install the ducts and all the rest according to instructions?
As a customer and unfortunately also a layman, can I influence this at all in any way?

Thanks in advance...

First of all, the question is, who actually plans such a ventilation system?

That is done by the heating technician/plumber or whoever is knowledgeable about it.

As a customer and unfortunately a layman, can I influence the whole process in any way?

You have to discuss that with the plumbing person. Why should you influence it as a layman?
Regarding your current questions, there is certainly more information available by searching the forum for “Controlled residential ventilation.”

Hello Dany250,

we have been running a Vitovent 300W continuously on level 3 for over 3 years. Due to the valves in the individual rooms, you can't hear anything at all. Only the device itself can be heard in the technical room and very quietly in the garden, where the connection for the exhaust air is located.

The system was planned for us by the manufacturer. We have a document with 9 pages listing all the details. The system was then installed by the contracted company accordingly.

Another document provides important installation instructions. Here is an excerpt regarding the question: